There has been known a field-sequential image display device for displaying a plurality of subframes in one frame period. For example, a typical field-sequential image display device is provided with a backlight including red, green, and blue light sources, and displays red, green, and blue subframes in one frame period. When the red subframe is to be displayed, a display panel is driven based on red video data, and the red light source emits light. Subsequently, the green subframe and the blue subframe are displayed in a similar manner. The three subframes displayed in a time-division manner are synthesized on retinas of an observer by an afterimage phenomenon, and recognized as one color image by the observer.
In the field-sequential image display device, when a line of sight of the observer moves within a display screen, the observer may see the colors of the respective subframes separate from each other (this phenomenon is called color breakup). As a method for suppressing the color breakup, there is known a method of displaying at least one color component of red, green and blue in two or more subframes in one frame period. For example, in a field-sequential image display device for displaying white, red, green, and blue subframes in one frame period, the red color component is displayed in the red and white subframes, the green color component is displayed in the green and white subframes, and the blue color component is displayed in the blue and white subframes.
In relation to the present invention, the following techniques have been known. Patent Document 1 describes that in a field-sequential image display device for displaying white, red, green, and blue subframes in one frame period, a display gradation level which is lower than the lowest value of the display gradation levels of red, green, and blue pixel data is defined as white pixel data, and the white pixel data is subtracted from the red, green, and blue pixel data.
Patent Document 2 describes that in a field-sequential display device for displaying at least each one of a three primary color subfield that displays red, green, or blue video, an in-between color subfield that displays in-between color video, and an achromatic color subfield that displays achromatic color video in one frame period, brightness of a video signal is distributed preferentially in the order of the achromatic color subfield, the in-between color subfield, and the three primary color subfield. Paragraph 0047 describes that a distribution ratio of color components except an achromatic color component is determined in accordance with which of color breakup or color rainbow is to be reduced more.
Patent Document 3 describes that in a field-sequential liquid crystal display device for displaying white, red, green, and blue subframes in one frame period, gradation of white is determined from gradation of red, green, and blue, brightness of four colors is calculated from the gradation of four colors, the brightness of red, green, and blue is determined based on the brightness of white, and the gradation of red, green, and blue is calculated from the brightness of red, green, and blue.